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Chondrocytes present in articular cartilage survive as a resident cell population throughout the lifespan of the individual organism. However, articular chondrocytes as other cells also undergo apoptosis and there is an ever increasing list of diverse stimuli that can induce this phenomenon in vitro. Our main interest was to investigate potential cytotoxic effects of vitamin C (L-ascorbic acid) on human articular chondrocytes. The present study suggests that vitamin C can induce apoptosis in a cell culture of chondrocytes after 18 h of cultivation. Apoptosis-inducing activity of L-ascorbic acid is dose dependent and significantly affected by the presence of serum. The increased number of vitamin C induced apoptotic cells was associated with DNA fragmentation and morphological changes of the cells.

Basic functional test for evaluation of in vitro cultured human dendritic cells (DC) is primary allogeneic one-way mixed lymphocyte reaction (MLR). In this way, one can evaluate stimulating capacity, which is a basic characteristic of DC. The proliferation of cells is measured through incorporation of 3 H-thymidine. Normally proliferation is measured at days 5-7. We studied kinetics of proliferative responses initiated with different stimulating cell suspensions to evaluate differences and possibly reduce time needed to perform this test.Gradual increase in response from days 1 to 7 and a significant difference from controls (peripheral blood mononuclear cells) seen from day 4 was noted if macrophages were used as stimulators. A consistently higher proliferation, compared to controls, was always found already on day 2 when mature DC were used as stimulators. The reaction peaked 2 to 3 days earlier and was also more than two times more intense.This maximal and significantly higher response, consistently seen already after 48 hours, allows us to confirm the presence of mature DC in stimulating suspensions much earlier than previously.